Systems, employed in cargo aircraft, for ventilating an aircraft cabin used as a cargo compartment comprise at present usually a piccolo pipe installed directly beneath the cabin ceiling. The piccolo pipe is provided with a plurality of air outlet openings, through which air flowing through the piccolo pipe can be blown out of the piccolo to pipe into the aircraft cabin. A ventilating system having a piccolo pipe as the central element for supplying ventilating air into an aircraft cabin is distinguished by a low weight and a low installation space volume. Furthermore, air blowing-out speeds of up to 15 m/s are attained with a ventilating system of this type. Owing to the blowing-out angle of the air from the piccolo pipe, intensive air mixing occurs in the aircraft cabin, making it virtually impossible to control different temperature zones.
Owing to their high air blowing-out speeds which are advantageously usable in a cargo aircraft, ventilating systems equipped with a piccolo pipe are, however, unsuitable for use in a passenger aircraft. At a blowing-out speed of the air from the piccolo pipe of up to 15 m/s, air speeds above 2 m/s could possibly occur in a passenger area of the aircraft cabin. These air speeds are, however, significantly above the comfort limit for people of about 0.35 m/s.
For this reason, ventilating systems with a central air supply pipe arranged in the region of the ceiling of the aircraft cabin and with a large number of branch pipes connected to the central air supply pipe are usually employed in passenger aircraft. The branch pipes lead the air to air outlets distributed in the aircraft cabin, the air outlets each being arranged and dimensioned such that a desired volume flow, a desired air exit angle and a desired maximum air blowing-out speed is achieved in the region of the air outlets. The disadvantages of known ventilating systems suitable for use in passenger aircraft are their relatively high weight and their large installation space requirement, particularly of the branch pipes.
In the case of an aircraft which, as required, is to be employed both as a cargo aircraft and for passenger transport, the basic problem is therefore to equip this aircraft with a ventilating system which meets the performance requirements made of the ventilating system in both applications. For example, it is known to equip an aircraft, designed for mixed use as a freighter and for passenger transport, with a ventilating system which comprises a full passenger cabin air supply system with branch pipes and with passenger air outlets distributed in the aircraft cabin. When this aircraft is to be used as a cargo aircraft, the cabin fittings installed for passenger transport are removed. However, the passenger cabin air supply system remains for the most part in the aircraft, in order to reduce the conversion time. In addition, to achieve the high blowing-out speeds of the air into the aircraft cabin which are desired for cargo transport, injector air outlets are connected to the central air supply of the ventilating system.
The present invention is directed to the object to provide a system and a method for ventilating an aircraft cabin which enable, in an aircraft which is to be employed both as a cargo aircraft and for passenger transport, optimum ventilation and multiple-zone temperature control of the aircraft cabin in both applications.